Hemifacial microsomia is the second most common craniofacial malformation, yet there have been few studies of its impact on affected children. We propose to conduct the first large scale follow-up study of children affected with hemifacial microsomia, to evaluate psycho-social, dental, orthodontic, and medical sequelae. The study design features 280 cases and 884 age and geographically matched controls from across the U.S. and Canada who were previously enrolled in a case control study of pregnancy risk factors from 1997 to 2002. The case group includes a range of phenotypes from isolated mild facial asymmetry to severe mandibular, auricular, and orbital hypoplasia with cranial nerve paralysis and extracranial malformations. In the proposed project, data will be collected when study subjects are 6.0 to 7.5 years of age, using valid and reliable tools that were specifically developed for this age group. Information will be provided by cases and controls and their parents, teachers, and clinicians. We will measure quality of the parent-child relationship and marital, family, and child functioning with the Parenting Stress Index; pro-social behaviors, communication skills, self-control, peer popularity, and academic ability with the Child Behavior Checklist, Social Competance Scales (for both parents and teachers), Social Competance and Behavior Evaluation Short Form, and the Teacher Report Form; quality of life and adaptive functioning with PedsQL 4.0; and neurocognition with the Visual Motor Integration test, Peabody Picture Vocabulary Test-Ill, and Teacher Report Form. Composite scores will be calculated for each psycho-social domain. Scores will be compared between cases and controls, and among phenotypic case subgroups. Orthodontic and dental outcomes will include caries, hypodontia, malocclusion, periodontal status, and overall oral health. Questionnaires will be sent to case and control dentists and, if applicable, orthodontists. Copies of dental radiographs will be examined by an oral surgeon and an orthodontist and scored for hypodontia. We will obtain copies of cases' medical records from all specialists. Systematic review of medical records will be performed to tally all surgeries (e.g., orthognathic), treatments (e.g., antibiotic prophylaxis), interventions (e.g., hearing aids), and other speciality consultations. Dental, orthodontic, surgical, auditory, and other outcomes will be described for cases according to phenotype.